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Subject: Re: [PATCH AUTOSEL 5.3 15/71] rbd: fix response length parameter for
 encoded strings
To:     Sasha Levin <sashal@kernel.org>, Ilya Dryomov <idryomov@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
        Dongsheng Yang <dongsheng.yang@easystack.cn>,
        Ceph Development <ceph-devel@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>
References: <20191001163922.14735-1-sashal@kernel.org>
 <20191001163922.14735-15-sashal@kernel.org>
 <CAOi1vP-2iSHxJVOabN05+NCiSZ0DxBC9fGN=5cx98mk5RvaDZA@mail.gmail.com>
 <20191008212944.GD1396@sasha-vm>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <ecddc946-4fbf-4bb2-aac2-689135473f36@kernel.dk>
Date:   Tue, 8 Oct 2019 21:45:18 -0600
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On 10/8/19 3:29 PM, Sasha Levin wrote:
> On Tue, Oct 01, 2019 at 07:15:49PM +0200, Ilya Dryomov wrote:
>> On Tue, Oct 1, 2019 at 6:39 PM Sasha Levin <sashal@kernel.org> wrote:
>>>
>>> From: Dongsheng Yang <dongsheng.yang@easystack.cn>
>>>
>>> [ Upstream commit 5435d2069503e2aa89c34a94154f4f2fa4a0c9c4 ]
>>>
>>> rbd_dev_image_id() allocates space for length but passes a smaller
>>> value to rbd_obj_method_sync().  rbd_dev_v2_object_prefix() doesn't
>>> allocate space for length.  Fix both to be consistent.
>>>
>>> Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
>>> Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
>>> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
>>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>>> ---
>>>   drivers/block/rbd.c | 10 ++++++----
>>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
>>> index c8fb886aebd4e..69db7385c8df5 100644
>>> --- a/drivers/block/rbd.c
>>> +++ b/drivers/block/rbd.c
>>> @@ -5669,17 +5669,20 @@ static int rbd_dev_v2_image_size(struct rbd_device *rbd_dev)
>>>
>>>   static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
>>>   {
>>> +       size_t size;
>>>          void *reply_buf;
>>>          int ret;
>>>          void *p;
>>>
>>> -       reply_buf = kzalloc(RBD_OBJ_PREFIX_LEN_MAX, GFP_KERNEL);
>>> +       /* Response will be an encoded string, which includes a length */
>>> +       size = sizeof(__le32) + RBD_OBJ_PREFIX_LEN_MAX;
>>> +       reply_buf = kzalloc(size, GFP_KERNEL);
>>>          if (!reply_buf)
>>>                  return -ENOMEM;
>>>
>>>          ret = rbd_obj_method_sync(rbd_dev, &rbd_dev->header_oid,
>>>                                    &rbd_dev->header_oloc, "get_object_prefix",
>>> -                                 NULL, 0, reply_buf, RBD_OBJ_PREFIX_LEN_MAX);
>>> +                                 NULL, 0, reply_buf, size);
>>>          dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
>>>          if (ret < 0)
>>>                  goto out;
>>> @@ -6696,7 +6699,6 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
>>>          dout("rbd id object name is %s\n", oid.name);
>>>
>>>          /* Response will be an encoded string, which includes a length */
>>> -
>>>          size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;
>>>          response = kzalloc(size, GFP_NOIO);
>>>          if (!response) {
>>> @@ -6708,7 +6710,7 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
>>>
>>>          ret = rbd_obj_method_sync(rbd_dev, &oid, &rbd_dev->header_oloc,
>>>                                    "get_id", NULL, 0,
>>> -                                 response, RBD_IMAGE_ID_LEN_MAX);
>>> +                                 response, size);
>>>          dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
>>>          if (ret == -ENOENT) {
>>>                  image_id = kstrdup("", GFP_KERNEL);
>>
>> Hi Sasha,
>>
>> This patch just made things consistent, there was no bug here.  I don't
>> think it should be backported.
> 
> I'll drop it, thanks!

How did it even get picked up, it's not marked for stable?

-- 
Jens Axboe